Pirfenidone is small drug molecule whose chemical name is 5-methyl-1-phenyl-2-(1H)-pyridone. It is a non-peptide synthetic molecule with a molecular weight of 185.23 daltons. Its chemical elements are expressed as C12H11NO, and its structure and synthesis are known. Pirfenidone is manufactured commercially and being evaluated clinically as a broad-spectrum anti-fibrotic drug. Pirfenidone has anti-fibrotic properties via: decreased TGF-β expression, decreased TNF-α expression, decreased PDGF expression, and decreased collagen expression.
Pirfenidone is being investigated for therapeutic benefits to patients suffering from fibrosis conditions such as Hermansky-Pudlak Syndrome (HPS) associated pulmonary fibrosis and idiopathic pulmonary fibrosis (IPF). Pirfenidone is also being investigated for a pharmacologic ability to prevent or remove excessive scar tissue found in fibrosis associated with injured tissues including that of lungs, skin, joints, kidneys, prostate glands, and livers. Published and unpublished basic and clinical research suggests that pirfenidone may safely slow or inhibit the progressive enlargement of fibrotic lesions, and prevent formation of new fibrotic lesions following tissue injuries.
As an investigational drug, pirfenidone is provided in tablet and capsule forms principally for oral administration. Various formulations have been tested and adopted in clinical trials and other research and experiments. The most common adverse reactions or events associated with pirfenidone therapy (>10%) are nausea, rash, dyspepsia, dizziness, vomiting, and photosensitivity reaction, and anorexia. Many of these effects can interfere with everyday activities and quality of life. These effects appear to be dose related. The adverse reactions associated with pirfenidone therapy are exacerbated when pirfenidone is administered at higher doses. In comparison to studies performed to determine the effects of pirfenidone therapy on patients, relatively little was known about the effects of pirfenidone when used in combination with other therapeutics.
Pirfenidone has been shown to be metabolized by isoforms of the cytochrome P450 (CYP) protein (Report on the Deliberation Results, Evaluation and Licensing Division, Pharmaceutical and Food Safety Bureau, Ministry of Health Labour and Welfare, Sep. 16, 2008). Specifically, several CYP isoforms (CYP1A2, 2C9, 2C19, 2D6 and 2E1) were involved in the earliest stages of oxidative metabolism of pirfenidone.
Activity of CYPs in patients who smoke is significantly increased over their non-smoking counterparts.